#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include<string.h>
int main() {
    char num1[501];
    int num2[128];
    memset(num2, 0, sizeof(int) * 128);
    int count = 0;
    scanf("%s", num1);
    for (int i = 0; num1[i] != '\0'; i++)
    {
        if (num2[(int)num1[i]] == 0)
            count++;
        num2[(int)num1[i]] = 1;
    }
    printf("%d", count);
    return 0;
}